DE60031604T2 - Medium for optical recording - Google Patents

Description

The The present invention relates to an optical information recording medium and more particularly an optical information recording medium, which is appropriately used as a recording medium for music.

optical Information recording media on which recorded information are and of which the information recorded by a laser light or the like, hot optical disks (optical discs), and of these are CDs (compact discs) for playing of music the most widely known. In addition, also become writeable optical information recording media (CD-R). In these Optical information recording media becomes a digital recording / reproducing method used in which the recording is performed by analog signals in converted digital signals and recorded the digital signals The playback will be done by converting the digital signals into analog signals and playing back the analog signals. Even if in this digital recording / reproduction method error while the time span from recording to playing, the Errors are corrected so that the original analog signals can be reproduced if the playback device is able to read coded pulse trains. This became conventional assumed that the structure of the optical information recording medium even the recording / reproduction quality has little effect Has.

It There is one, albeit small, number of inventions that arise the effects of the structure of an optical information recording medium focus on the recording / reproduction quality. So discloses, for example, Japanese Patent Application Laid-open (JP-A) No. 2-214078 discloses an invention which improves the reproduction sound quality of a Improved compact disc. In this invention of JP-A-2-214078 a surface an optical disc coated with a layer consisting of a soft flexible material, such as rubber, and vibration absorbs and absorbs, and the natural frequency of the plate is determined by the soft, flexible Layer absorbed to improve the quality of sound reproduction. A problem with this optical disk disclosed in JP-A-2-214078 however, is that it generates vibrations at one frequency which differs from the natural frequency of the optical disk, so that does not always achieve an improvement in sound quality becomes. About that In addition, problems arise with the handling of the plates, that the surface the plate with a material such as rubber or like, is coated, causing several plates together stick it and it is difficult with a pen on the surface of the Write a record, and the like.

There The popularity of CD-Rs has increased in recent years copy-protected CD-Rs exclusively for music developed, and about it In addition, an improvement in the recording / reproduction quality (in particular the sound quality) required.

It An object of the present invention is an optical information recording medium with improved sound quality provide.

In order to achieve the above object, the present invention provides an optical information recording medium comprising: either a plate-shaped transparent substrate on which a recording section consisting of a light-absorbing layer in which information can be recorded with laser light is provided, or a plate-shaped transparent substrate on which a recording section is provided on which information is recorded that can be reproduced by a laser light; a light-reflecting layer provided on the recording section; and a stabilizing layer made of a material having a density of 1.4 to 4.2 g / cm ³ and provided on the light-reflecting layer such that a center of gravity of the optical information recording medium is within a range of 15% of one Radius of the optical information recording medium from a center of the optical information recording medium is located.

Since this optical information recording medium comprises the stabilizing layer of a material having a density of 1.4 to 4.2 g / cm ³ , which is relatively heavy in comparison with other materials of the medium, tones can be obtained whose balance is in the middle and low frequency ranges audible range is good and stable and pleasant. Moreover, the stabilizing layer is provided such that the center of gravity of the optical information recording medium is within a range of 15% of the radius of the optical information recording medium around the center of the optical information recording medium to prevent excessive radial impact of the optical information recording medium optical information recording medium to avoid. The reasons for the improved sound quality of the optical information recording medium are not clear, but it is believed that the stabilizing layer vertically compresses the optical information recording layer, so that the optical information recording medium is stable and, as a result, vibrations in the rotation are suppressed, thereby improving sound quality.

SHORT DESCRIPTION THE DRAWINGS

1 Fig. 10 is a sectional view of an example of a structure of the layers of an optical information recording medium of the present invention.

2 Fig. 10 is a sectional view of an example of another structure of the layers of an optical information recording medium of the present invention.

3A and 3B 10 are sectional views of an example of another structure of the layers of an optical information recording medium of the present invention.

4 Fig. 12 is a plan view illustrating the relationship between the position of the center of gravity and the position of the center of the optical information recording medium of the present invention.

5A Fig. 10 is a sectional view of another optical information recording medium of the present invention.

5B FIG. 11 is a plan view of the optical information recording medium. FIG 5A ,

6 Fig. 12 is a plan view of another optical information recording medium of the present invention.

7 Fig. 12 is a plan view of another optical information recording medium of the present invention.

8th is a perspective view of a CD-R according to the present invention.

9 is a perspective view of another CD-R according to the present invention.

10 Fig. 12 is a graph illustrating the transmission frequency bands of the substrates.

in the Next, an optical information recording medium of the Detailed Description of the Invention described.

First, the structure of the optical information recording medium of the present invention will be described. When the optical information recording medium of the present invention is a CD which is an optical information recording medium for reproduction only, as in 1 As shown, the optical information recording medium is structured such that at least one light-reflecting layer 14 and a stabilizing layer 16 in this order on a plate-shaped substrate 12 are provided on which information is recorded, which can be reproduced by a laser light. When the optical information recording medium of the present invention is a CD-R which is a recordable optical information recording medium, or a CD-RW which is a rewritable optical information recording medium as in 2 As shown, the optical information recording medium is structured such that at least one light-reflecting layer 20 on which information can be recorded by laser light, the light reflecting layer 14 and the stabilizing layer 16 in this order on a plate-shaped, transparent substrate 18 be provided, on which a Vorrille is formed. In addition, as in the 3A and 3B shown by providing a colorant layer 24 between the light-reflecting layer 14 and the stabilizing layer 16 the sound quality will be further improved. In addition, if necessary, protective layers or intermediate layers can be provided. The respective layers will be described in detail below.

The stabilization layer 16 is formed of a material having a density of 1.4 to 4.2 g / cm ³ . If the density of the material is less than 1.4 g / cm ³ , there will be no acoustically perceptible improvement in tone quality achieved. If the density of the material is greater than 4.2 g / cm ³ , the load applied to the optical information recording medium by the rotating medium is too high. The density of the material is preferably between 1.4 to 3.0 g / cm ³ , and ideally the density is between 1.4 and 2.0 g / cm ³ . Provided that their density is in the above ranges, inorganic substances such as SiO ₂ , SiO ₂ , MgF ₂ , SnO ₂ , Si ₃ N ₄ , TiO ₂ and BaO ₂ , and organic substances such as thermoplastics, thermosetting plastics and UV-curing plastics, as materials for the stabilizing layer 16 be used. Of these materials, titanium compounds, especially TiO ₂ , are preferable from the viewpoint of high specific gravity and easily adjustable density. These materials may be used alone or in combinations of two or more materials.

In a case where an inorganic substance such as TiO ₂ , BaO ₂ or the like is used as a material for the stabilizing layer 16 is used, the stabilizing layer 16 are formed by dispersing the inorganic substance in a binder such as a plastic curing under ultraviolet light, and the binder with the dispersed inorganic substance by means of screen printing or the like on the light-reflecting layer 14 is applied. At this time, the mixing ratio of the inorganic substance and the binder resin may be adjusted so that the mixture has a desired density. The stabilization layer 16 Further, it can be formed by making the binder resin in which the inorganic substance is dispersed into a film by an extrusion method, and then applying this film to the light-reflecting layer using an adhesive. In addition, the stabilization layer 16 also be formed by the inorganic substance directly by vacuum evaporation, vapor deposition or the like on the light-reflecting layer 14 is applied.

When a thermoplastic resin or a thermosetting plastic as a material for the stabilizing layer 16 is used, the stabilizing layer 16 are formed by dissolving the plastic in a suitable solvent to prepare a coating solution, and then applying the coating solution to the light-reflecting layer by screen printing or the like 14 applied and the applied layer is dried. In particular, when using a plastic that cures under ultraviolet (UV) light, the stabilizing layer 16 be formed by the UV-curable plastic or a coating solution in which the UV-curing resin is dissolved in a suitable solvent, on the light-reflecting layer 14 applied and the applied film is cured by exposure to UV light. UV curable resins are preferable because they shrink little during curing (crosslinking), preventing the plate from warping.

As in the 1 to 3 shown, the stabilization layer 16 be provided so as to cover the entire surface of the light-reflecting layer 14 covered, or she can, as in the 5A . 5B . 6 and 7 shown only on a part of the surface of the light-reflecting layer 14 to be provided. In the 5A and 5B is the stabilization layer 16 over the entire circumference of the outer peripheral part of the surface of the light-reflecting layer 14 provided. In 6 is the stabilization layer 16 on parts of the outer peripheral part of the surface of the light-reflecting layer 14 provided. In 8th is the stabilization layer 16 radially on the surface of the light reflecting layer 14 provided.

To avoid a radial strike, as in 4 In all these cases, the stabilization layer is shown 16 provided so that the center of gravity G of the optical information recording medium is within a range (indicated by hatching) which is 15% of the radius of the optical information recording medium around the center C (center of the circle of the optical information recording medium) of the optical information recording medium.

The position of the center of gravity G is preferably within a range of 12% of the radius r of the optical information recording medium from the center C, and it is more preferable that the position is within a range of 10%. For example, in a CD, a CD-R or a CD-RW, since the radius r of the optical information recording medium is usually 6 cm, the stabilizing layer 16 is provided so that the center of gravity G is within an area having a radius of 9 mm around the center C, and preferably within an area having a radius of 7.2 mm, and it is more preferable that the center of gravity be within a range of Area is located with a radius of 6.0 mm.

In addition, the arrangement of the stabilizing layer influences 16 how the sound propagates from the sound source such as a speaker or the like. Is the stabilization layer 16 on the entire surface of the light-reflecting layer 14 provided, the sound propagates in all directions. However, if the stabilizing layer 16 only on the outer peripheral part of the surface of the light-reflecting layer 14 is provided as in 5A shown, the sound propagates horizontally. However, although horizontally propagating sound is desirable from the standpoint of musical enjoyment, the structure of the sound source, such as that of a loudspeaker, makes it difficult to achieve such sound. Thus, to achieve such sound, the stabilizing layer is 16 preferably on the outer peripheral part of the surface of the light-reflecting layer 14 provided. The stabilization layer 16 is preferably provided in an area on the outside of a range of 50% of the radius r of the optical information recording medium around the center C of the optical information recording medium (the center C of the optical information recording medium is at 0% of the radius r), and still is more preferable to be provided within a range on the outside of a range of 54% of the radius r of the optical information recording medium, and even more preferable to be in an area on the outside of a range of 60% of the radius r of the optical Information recording medium is provided. For a CD, a CD-R or a CD-RW, the stabilization layer becomes 16 is preferably provided in an area on the outside of a region having a radius of 3 cm around the center C, and it is more preferable that it be in an area on the outside of a region having a radius of 3.24 cm about the center C around, and it is even more preferable that it be provided in an area on the outside of a 3.6 cm radius area around the center point C.

The thickness of the stabilization layer 16 is taking into account the density of the material of the stabilizing layer 16 and the surface area of the parts of the surface of the light-reflecting layer 14 on which the stabilizing layer 16 is provided, so that a mass of about 0.001 to about 5.0 g is added to the entire optical information recording medium. The thickness of the stabilization layer 16 is preferably between 1 to 300 microns, and it is more preferable that it is between 3 and 200 microns. The thickness of the stabilization layer 16 preferably corresponds to 1.5 to 6 times the thickness of the colorant layer 24 which will be described later. Just like the colorant layer 24 it is preferable that the stabilizing layer 16 a colorant whose wavelength of maximum reflection is in the band of 400 to 560 nm.

The colorant layer 24 contains a colorant whose maximum reflection wavelength is in the 400 to 560 nm band.

The wavelength the recording / reproducing light of recording / reproducing apparatuses, currently used is 780 nm. Since the colorant layer, the reflective between the stabilizing layer and the light Layer is provided, containing a colorant whose wavelength of the maximum Reflection in the band from 400 to 560 nm, which is the complementary color of the Is recording / playback light, the purity improves of sound, and sound quality will be improved even further. Although the reasons for the improvement of purity Of clay are not clear, it is believed that the colorant layer Stray light from the light-reflecting layer absorbs what to reduce typing or reading errors Recording and playing leads, because these errors are due to stray light.

The colorant may be a pigment or a dye, and from the standpoint of appearance, dyeing is preferably carried out using a colored glaze. If a colored glaze is used, the parts to which the colored glaze has been applied may have the average reflectance of light in a wavelength range of 400 to 700 nm influenced to be in a range of 3 to 80%. Thus, the rainbow-colored reflection characteristic based on optical diffraction and on the metallic luster possessed by the optical disk itself can be utilized. In this document, "colored glaze" refers to inks, for example, pigment inks, which are different from other inks in that the light diffusion of normal inks is high and their normal reflection is virtually zero The term "colored glaze" covers colorless, transparent Inks do not turn off. UV curable inks are preferred examples of colored glazes. When at least two or more colored glazes having different absorption wavelengths are used, by applying these glazes one above the other, the wavelength spectrums of the reflected light can be adjusted on the surface of an optical information recording medium having an inscription or the like printed on one surface opposite to the side the recording light and the playback light to meet. If, for example, a blue glaze is applied to a part to which a yellow glaze has already been applied, the parts to which the glazes have been applied in this way are colored green by color mixing according to the subtractive color mixture. In addition, the thickness of the colorant layer is 24 preferably between 1 and 20 microns, and it is more preferable that it is between 5 and 10 microns.

The transparent substrates 12 and 18 are plate-shaped, transparent plastic plates. In this case, "transparent" means transparent with respect to the reproducing light or transparent with respect to the recording light and the reproducing light. Specifically, "transparent" means that the recording and / or reproducing light are not absorbed. Examples of the material for the substrate are polycarbonates; Acrylic resins, for example polymethylmethacrylate; Vinyl chloride plastics, for example, polyvinyl chloride, and vinyl chloride copolymers; epoxy resins; amorphous polyolefins, glass, polyester and the like. If desired, combinations of these materials may also be used. Among these materials, amorphous polyolefin and polycarbonate are preferred, and polycarbonate is particularly preferred from the viewpoint of moisture resistance, dimensional stability and cost. In addition, the thickness of the transparent substrates is 12 and 18 preferably 1.2 ± 0.2 mm.

Tracking grooves for tracking and pits expressing information such as digital signals are formed in advance by injection molding in the transparent substrate 12 a CD formed. In addition, guide grooves and pregrooves representing information such as address signals are formed in the transparent substrate 18 a CD-R or a CD-RW formed. The average pitch of these pregrooves is preferably 0.1 to 50 μm, it is more preferable that the average pitch is 0.2 to 30 μm, and it is more preferable that the average pitch is 0.3 to 10 μm. In addition, the average depth of these pregrooves is preferably 10 to 5,000 μm, more preferable that the average depth is 30 to 3,000 μm, and even more preferable to be 50 to 1,000 μm.

at a CD-R or a CD-RW, intended for use as a sound carrier can be an application code in advance, for example, a wobble, for the Vorrille be recorded, which is characterized in that the plate for the use as a sound carrier is provided.

A further improved sound quality can be achieved by using the transparent substrates 12 and 18 are used, which have a low light transmittance for light whose wavelengths are shorter than the wavelength for playback. Specifically, by the transparent substrates 12 and 18 for light in the wavelength band of 200 nm to a wavelength shorter by 50 nm than the reproduction wavelength, having an average light transmittance of 50% or less, preferably 40% or less, even more preferable is an average transmittance of 30% or less, an even greater improvement in sound quality can be achieved, and good sound quality can be maintained over a long period of time. The reason for improving the sound quality is not clear, however, assuming a 50% or more reduction in the average light transmittance for light in a wavelength band of 200 nm to a wavelength shorter by 50 nm than the reproducing wavelength in that light that is not equal to the playback light does not reach the detector during playback, and noise is reduced, thereby improving the sound quality. Moreover, it is believed that improving the opacity of the optical information recording medium results in that the improvement in sound quality can be maintained for a long period of time. For example, in a CD, a CD-R or a CD-RW, the reproduction wavelength is generally 780 nm, and the average light transmittance for light in the wavelength band of 200 to 730 nm is reduced to 50% or less. In a DVD, a DVD-R or a DVD-RW, the reproduction wavelength is generally 650 nm, and the average light transmittance for light in the wavelength band of 200 to 600 nm is reduced to 50% or less. An adaptation of the light transmittances of the transparent substrates 12 and 18 can by coloring the transparent substrates 12 and 18 by using a colorant such as a pigment, a dye or the like. In particular, by appropriately varying the colorant amount mixed under the substrate, the light transmittances of the transparent substrates 12 and 18 be adjusted.

The transparent substrates 12 and 18 For example, when molding the transparent substrates 12 and 18 by coloring a colorant under a plastic, such as polycarbonate, which is the material for the substrate. The transparent substrates 12 and 18 can also be colored by the transparent substrates 12 and 18 are dipped in a dye after being molded. In addition, when a colorant is mixed in the plastic, the Substratma terial, the colorant can be mixed directly into the plastic, which represents the substrate material. In addition, plastic pellets mixed in advance with a colorant (these pellets are called parent color) may be mixed with the plastic constituting the substrate material.

The colorant and the parent color used to color the transparent substrates 12 and 18 are not specifically limited. Existing pigments or dyes which absorb light in a wavelength range of 200 nm to a wavelength 50 nm shorter than the reproduction wavelength, or an appropriate parent color containing such a pigment or dye, can be selected according to the wavelength of the playback light. These colorants may be used singly or as combinations of two or more substances. In order to prevent color fading, it is preferable that the pigment or dye has excellent light and heat resistance. Furthermore, a dye for the recording layer described below is generally not stable, but further, dyes of the same type as the dye in the recording layer may be used if the dye exists in a stable state within the substrate can. The amount of in the transparent substrates 12 and 18 The colorant contained is preferably 0.1 to 20% by weight, and it is more preferable that the proportion is 0.5 to 10% by weight. If the amount of the colorant contained is too small, the colorant will not be uniformly mixed under the substrate. If the amount of colorant contained is too high, a large amount of the stock color is used, a large-scale manufacturing process is required, and the manufacturing cost increases, which is undesirable. Preferably, in a range of 50 nm around the recording wavelength and the reproducing wavelength, no absorption of the light by the colorant takes place so as not to hinder the passage of the recording light or the reproducing light, and it is preferable that in a range of 100 nm around the recording wavelength and the reproduction wavelength, no absorption of the light by the colorant takes place.

The light transmission of the transparent substrates 12 and 18 can be achieved by providing a light transmittance matching layer on the surface of the transparent substrate 12 or 18 be adapted, which contains a colorant. From the viewpoint of ease of formation, it is preferable to use the light transmittance matching layer on the surface of the transparent substrate 12 or the transparent substrate 18 on the side where the recording light and the playback light impinge. The light transmittance matching layer may further be on the surface of the transparent substrate 12 or the transparent substrate 18 are applied, which is opposite to the side on which the recording light and the reproducing light impinge. The light-transmissive reflection layer may be formed as follows: One or more of the foregoing colorants and a binder are dissolved or dispersed in a suitable solvent to prepare a coating solution, then the coating solution is applied to the substrate surface by a coating method such as spin coating or the like applied. The thickness of the light transmittance adjusting layer is preferably from 0.5 to 30 μm, and it is more preferable that the thickness is from 1 to 10 μm.

The light reflecting layer 14 is provided on the substrate to improve the reflection. When the light-absorbing layer 20 , which will be described later, becomes the light-reflecting layer 14 on the light-absorbing layer 20 provided. Any light-reflecting substance that reflects laser light to a high degree may be used as the material for the light-reflecting layer 14 be used. The reflection of the material is preferably 30% or more, it is more preferable that the reflection is 50% or more, and it is more preferable that the reflection is 70% or more. Examples of materials for the light-reflecting layer 14 include metals and semimetals such as Mg, Se, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Co, Ni, Ru, Rh, Pd, Ir, Pt , Cu, Ag, Au, Zn, Cd, Al, Ga, In, Si, Ge, Te, Pb, Po, Sn and Bi, and stainless steel. Of the substances mentioned, Cr, Ni, Pt, Cu, Ag, Au, Al and stainless steel are to be preferred. These materials may be used alone or in combinations of two or more materials. In addition, the substances can also be used as an alloy. It is especially preferable that the material of the light reflecting layer 14 Au, Ag, Al or an alloy of said metals. The light reflecting layer 14 can be formed by coating, vapor deposition or ion plating. The thickness of the light-reflecting layer 14 is generally in the range between 10 and 800 nm, preferably the thickness is in the range between 20 and 500 nm, and it is more preferable that the thickness is in the range between 50 and 300 nm.

In a recordable optical information recording medium, the light absorbing layer becomes 20 between the transparent substrate 18 and the light reflecting layer 14 provided. The Light absorbing layer 20 may be a dye recording layer in which recording is performed by a dye, a phase change recording layer in which recording is performed by a phase change, or a photomagnetic recording layer in which recording is performed by photomagnetism. A dye-recording layer is preferable from the viewpoints of ease of formation and stability.

Of the Dye used in the dye recording layer is not specifically limited and examples of usable dyes include cyanine dye, phthalocyanine dye, Imidazoquinoxaline dye, pyryl dye, thiopyryl dye, Azulene dye, squaryl dye, metal complex salts with Ni, Cr and the like, naphthoquinone dye, anthraquinone dye, Indophenol dye, indoaniline dye, triphenylmethane dye, Merocyanine dye, oxonol dye, ammonium dye, diammonium dye, Nitroso compounds and the like.

The Dye-recording layer is prepared by applying a solution, in which a dye is dissolved in a suitable solvent. The concentration of the dye in the coating liquid is generally 0.01 to 15% by weight, preferably 0.1 to 10 percent by weight, it is more preferable that the concentration 0.5 to 5 weight percent, and it is even more preferable that the concentration be 0.5 to 3 weight percent. examples for solvent for the coating liquid for forming the dye-recording layer include esters, such as butyl acetate, glycol ether acetates and the like; Ketones such as methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone and the same; chlorinated hydrocarbons, such as Dichloromethane, 1,2-dichloroethane, Chloroform and the like; Amides, such as dimethylformamide and the same; Hydrocarbons, such as cyclohexane and the same; Ethers, such as tetrahydrofuran, ethyl ether, Dioxane and the like; Alcohols, such as, for example, ethanol, n-propanol, Isopropanol, n-butanol, diacetone alcohol and the like; fluorochemical Solvent, such as 2,2,3,3-tetrafluoropropanol and the like; glycol ethers, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Propylene glycol monomethyl ether and the like; and the same. Given the solubility of the dye used can the above solvents used individually or in combinations of two or more species. Preferably, fluorine-containing solvents, such as 2,2,3,3-tetrafluoropropanol and the like used. About that addition is the thickness of the dye-recording layer is generally 20 to 500 nm and preferably 50 to 300 nm.

If desired can Agents which prevent fading, and binders to the coating solution for Forming the dye-recording layer can be added. About that In addition, any additive may be of a variety of types Additives, such as antioxidants, ultraviolet light filtering Additives, plasticizers, lubricants and the like in accordance be used with the task. Representative examples of means which prevent fading are nitroso compounds, metal complexes, Diimmonium salts and ammonium salts. Examples of this will be for example, in the patents JP-A-2-300288, JP-A-3-224793, JP-A-4-146189 and the like disclosed. examples for Binders include natural ones organic polymers, such as gelatin, cellulose derivatives, Dextran, synthetic resin, rubber and the like; as well as synthetic organic polymers, such as hydrocarbon plastics (Polyethylene, polypropylene, polystyrene, polyisobutylene and the like), Vinyl plastics (polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymers and the like), acrylic resins (polymethyl acrylate, polymethyl methacrylate and the like), polyvinyl alcohol, chlorinated polyethylene, epoxy resins, Butyral plastics, such as phenol-formaldehyde plastics and the same. If a binder is used, its Amount generally 20 parts by weight or less, preferably 10 parts by weight or less, it is more preferable that the proportion is 5 parts by weight or less if the dye is 100 parts by weight.

Becomes the light-absorbing layer 20 provided on the surface of the transparent substrate 18 on which the light-absorbing layer 20 provided a sub-layer to improve the flatness and the adhesion and changes in the properties of the light-absorbing layer 20 to prevent. Examples of the material for the underlayer are polymers such as polymethylmethacrylate, acrylate-methacrylate copolymers, styrene-maleic anhydride copolymers, polyvinyl alcohol, N-methylolacrylamide, styrene-vinyltoluene copolymers, chlorosulfonated polyethylene, nitrocellulose, polyvinylchloride, chlorinated polyolefins, polyesters, Polyimide, vinyl acetate-vinyl chloride copolymers, ethylene-vinyl acetate copolymers, polyethylene, polypropylene, polycarbonate and the like; and surface modifying agents such as silane coupling agents or the like. The underlayer may be prepared as follows: The above-mentioned substance is dissolved or dispersed in a suitable solvent to prepare a coating liquid, and the coating liquid is applied to the Surface of the substrate by a coating method, such as Rotati onsbeschichten applied, dip coating, extrusion coating or the like. The thickness of the underlayer is preferably 0.05 to 20 μm, and it is preferable that the thickness is between 0.01 and 10 μm.

It is preferable that a protective layer on the light-reflecting layer 14 is provided to improve the resistance of the optical information recording medium to moisture and scratches. When a protective layer is provided, the stabilizing layer described above becomes 16 and the colorant layer 24 provided on the protective layer. Examples of the material used for the protective layer are inorganic substances such as SiO ₂ , SiO ₂ , MgF ₂ , SnO ₂ , Si ₃ N ₄ and the like; and organic substances such as thermoplastics, thermosetting plastics, UV curing resins and the like. The protective layer may be formed on the light-reflecting layer by, for example, laminating a film obtained by extruding a plastic by means of an adhesive. In addition, the protective layer may be formed by a method such as vacuum evaporation, vapor deposition, coating or the like. When a thermoplastic resin or a thermosetting resin is used as the material for the protective layer, the protective layer may be formed by dissolving the thermoplastic or thermosetting resin in a suitable solvent, thereby preparing a coating liquid, and then applying the coating liquid and dried. When a UV-curable resin is used as the material, the protective layer may be formed by applying the UV curable resin or a coating liquid in which the ultraviolet curing resin is dissolved in a suitable solvent, and the coated layer is cured (crosslinked) by irradiation with UV light. Various additives such as anti-static agents, antioxidants, UV filters and the like may be added to the coating liquid in accordance with the object. The thickness of the protective layer is generally in the range of 0.1 to 100 μm.

The 8th and 9 illustrate a CD-R which is a recordable optical information recording medium and which is the optical information recording medium of the present invention.

In the 8th The CD-R shown is formed by the plate-shaped, transparent substrate 18 in which there is a center hole in the central part, through the light-absorbing layer 20 formed from a dye-recording layer containing an organic dye through the light-reflecting layer 14 , the protective layer 26 , the colorant layer 24 and the stabilizing layer 16 , A spiral pregroove is on the transparent substrate 18 formed in a region which is within a predetermined radius and not equal to the peripheral part of the center hole and the outer peripheral part of the transparent substrate 18 is. The light-absorbing layer 20 is in the region of the transparent substrate 18 provided in which the Vorrille is formed. The light reflecting layer 14 is on the light-absorbing layer 20 provided to the light-absorbing layer 20 to cover, and the protective layer 26 is on the light reflecting layer 14 provided to the light reflective layer 14 to cover. The colorant layer 24 is on the protective layer 26 provided to the protective layer 26 to cover. The stabilization layer 16 is at the outer peripheral part of the surface of the colorant layer 24 provided.

In the 9 shown CD-R is structured in the same way as in 8th shown CD-R, except that the stabilizing layer 16 is provided on the entire surface, that is, it is provided to the colorant layer 24 to cover. For the in 9 shown CD-R will be given the same reference numbers as those in 8th CD-R used and the description of the same parts will be omitted.

The optical information recording medium of the present invention can also be used on DVDs (Digital Video Discs), such as DVDs, DVD-Rs, DVD-RWs and the like, the records are applied with an even higher one Enable density. A DVD has essentially the same structure as a CD, for example, a CD, a CD-R, a CD-RW or the like, except that with a DVD the distances the traces of the pits or those in the transparent one Substrate formed pregroove are narrower. In the same way as described above also the stabilizing layer and the colorant layer on the Light reflective layer or provided on the protective layer become.

DVD-Rs and DVD-RWs can be produced by laminating the plate-shaped transparent substrate on which at least the light-absorbing layer is provided and a protective substrate of the same size as the transparent substrate using an adhesive in such a way that the light-absorbing layer is arranged on the inner side. In this case, the stabilizing layer and the colorant layer may be provided on the protective substrate. In this laminated structure, a transparent substrate having a diameter of 120 ± 3 mm and a thickness of 0.6 ± 0.1 mm is generally used, and the thickness of the optical information recording medium after lamination is set to be about 1.2 ± 0.2 mm. The lamination may be carried out by using the ultraviolet curable resin used to form the protective layer or may be made by using a synthetic adhesive. The transparent substrate and the protective substrate may also be laminated to each other using double-sided adhesive tape. The pitch of the traces of the pits or the pregroove formed in the transparent substrate is generally in the range of 0.6 to 0.9 μm, and the depth of the pregroove is preferably 80 to 300 nm, and it is more preferable that that the depth is 100 to 250 nm. In addition, the half width of the pregroove is preferably in a range of 0.1 to 0.5 μm.

EXAMPLES

in the Hereinafter, the present invention will be described in detail by examples.

Examples 1 to 10, Comparative Examples 1 to 3

(Production of CD-R discs)

substrates (normal substrates) (diameter: 120 mm, thickness: 1.2 mm), the one spiral Vorrille (track pitch: 1.6 μm, Width of the pregroove: 0.4 μm, Depth of the pregroove: 0.16 μm) then own and manufactured by injection molding, were prepared using transparent polycarbonate pellets (PANLITE A D5503, manufactured by Teijin Co., Ltd.). There were 2.65 g of the following indolenine dye (A), 0.265 g of the following agent against color fading (B) and 0.133 g of a binder (CA-139, manufactured by Morton Co.) over 10 hours in 100 ml of 2,2,3,3-tetrafluoropropanol using an ultrasonic vibrator Solved (1800 W), whereby a coating liquid for the Recording layer was prepared.

Indolenine dye (A)

Means against color fading (B)

This coating solution was spin-coated by varying the rotational speed between 300 rpm and 4000 rpm on the pregroove-side surface of the above-mentioned Po lycarbonate substrates applied. The coated substrates were then dried so that a dye recording layer (thickness (within the pregroove): about 200 nm) was formed thereon. The conditions for forming the dye-recording layer were as follows: ambient temperature and humidity: 23 ° C, 50% RH; Temperature of the coating liquid: 23 ° C; Temperature of the substrate: 23 ° C; Speed of the ventilation air: 0.1 m / s. Thereafter, by vapor deposition of Ag on each of the substrates, a light-reflecting layer having a film thickness of 150 nm was formed on the dye-recording layer. Thereafter, a UV-curable plastic (SD-318, manufactured by DaiNippon Ink and Chemicals Co., Ltd.) was spin-coated on the light-reflecting layer formed on each of the substrates, the rotation speed varied between 50 rpm and 5000 rpm. After the coating, ultraviolet light from a high-pressure mercury lamp was irradiated from above, so that the ultraviolet-curing resin cured and formed a protective layer having a thickness of 8 μm.

• – Wellenlänge der maximalen Reflexion des Farbmittels
• – Vorhandensein oder Nichtvorhandensein einer Farbmittelschicht und Dicke, falls vorhanden,
• – Dichte des Materials für die Stabilisierungsschicht
• – Position der Stabilisierungsschicht
• – Dicke der Stabilisierungsschicht
• – Wellenlänge der maximalen Reflexion der Stabilisierungsschicht

A stabilizing layer or a colorant layer and a stabilizing layer were formed on the protective layer to obtain CD-Rs by varying the following conditions in various manners as shown in Table 1. For each of the CD-Rs, the center of gravity position essentially coincided with the center of the plate. When a stabilizing layer was provided on the outer peripheral part, the stabilizing layer was provided along the entire circumference in an area on the outside of a region that was r% of the radius of the CD-R disk from its center. Conditions:

• - Wavelength of the maximum reflection of the colorant
• Presence or absence of a colorant layer and thickness, if any,
• - Density of the material for the stabilization layer
• - Position of the stabilizing layer
• Thickness of the stabilizing layer
• - Wavelength of the maximum reflection of the stabilization layer

The nine musical compositions listed in the following Table 2 were recorded on the obtained CD-Rs with a commercially available CD-R recorder (recording wavelength 780 nm) drawn. Four music critics listened to the sound reproduction obtained by reproducing the recorded CD-Rs on a commercially available CD player (reproducing wavelength: 780 nm). The critics rated the sound quality based on the volume and purity of the sound, timbre, and sound field (propagation of the sound). The CD-R, which had no colorant layer and no stabilization layer, received a score of 70 points. This rating was used as a standard, the CD-Rs which showed a clear improvement in sound quality received a score of 80 points or more, and the CD-Rs which showed a considerable improvement in sound quality received a rating score of 90 points or more. The results of the evaluation are shown in Table 1.

As is clear from Table 1, the sound quality of the CD-Rs on which stabilizing layers were provided whose density was between 1.4 and 4.2 g / cm ³ was better evaluated than the sound quality of CD-Rs had no stabilization layers. In addition, the CD-R received at the Stabilization layer was provided on its outer periphery, the highest rating of CD-Rs having stabilization layers. The CD-R, having both a stabilizing layer and a colorant layer containing a colorant whose maximum reflection wavelength was in a band of 400 to 560 nm, received a particularly good rating of sound quality.

Examples 11 to 14, Comparative Example 4

One black colored Substrate (A) (thickness: 0.6 mm, inner diameter: 15 mm, outer diameter: 120 mm) on which a spiral Vorrille (width of the Vorrille: 300 nm, depth of the Vorrille: 150 nm) was trained, prepared by a plastic material in which 3.5% by weight of a parent color (MAKROLON DP1-1219, manufactured by Bayer Ltd.) with transparent polycarbonate pellets (PANLITE AD5503, manufactured by Teijin Co.) and processed by injection molding was formed. About that In addition, a violet colored Substrate (B) (thickness: 0.6 mm, inner diameter: 15 mm, outer diameter: 120 mm) on which a spiral Vorrille (width of the Vorrille: 300 nm, depth of the Vorrille: 150 nm) was formed, prepared by using a plastic material in which 4.0% by weight of a stock color (MAKROLON NEON RED 001, manufactured by Bayer Ltd.) with transparent polycarbonate pellets (PANLITE AD5503, manufactured by Teijin Co.) and processed by injection molding was formed.

The thus-produced colored substrate (A) had an average light transmittance of light in a wavelength region between 200 and 730 nm of 4%, and the thus-produced colored substrate (B) had an average light transmittance for light in a wavelength region between 200 and 730 nm of 47%. The above-mentioned transparent substrate, which was not colored and made of polycarbonate, had an average light transmittance of light in a wavelength range between 200 and 730 nm of 61%. The transmission spectra in the wavelength band of 200 to 800 nm of these substrates are shown in FIG 10 shown. The transmission frequency band of the colored substrate (A) is represented by the solid line, the transmission frequency band of the colored substrate (B) is represented by the dotted line, and the transmission frequency band of the transparent substrate which is not colored and formed of polycarbonate was, is represented by the dash-dot line. How out 10 As can be seen, the colored substrate (B) allowed the passage of light in a range of 400 nm and in a range of 600 nm, and had, as mentioned above, for a wavelength range between 200 and 730 nm, an average light transmittance of 47%.

A Dye-recording layer, a light-reflecting layer and a protective layer were prepared in the same manner as in Example 1 using the colored substrates (A) and (B). A stabilizing layer was formed on the protective layer, by varying various conditions to obtain CD-Rs.

The nine musical compositions listed in Table 2 were recorded on the obtained CD-Rs with a commercially available CD-R recorder (recording wavelength 780 nm). Four music critics listened to the sound reproduction obtained by reproducing the recorded CD-Rs on a commercially available CD player (reproducing wavelength: 780 nm). The critics rated the sound quality in the same way as in the previous examples. The results of the evaluation are shown in Table 1. As is apparent from Table 1, the CD-Rs having the colored substrate (A) or (B) and to which a stabilizing layer having a density of 1.4 to 4.2 g / cm ^{3 was} applied were given particularly high Ratings for the sound quality in the same manner as the CD-Rs on which the colorant layers were provided in Examples 6 to 10. In addition, the recorded CD-Rs of Examples 11 to 14 were irradiated with light for 100 hours using a light-fastness tester with a xenon lamp, after which four music critics listened to sound reproduction by playing the recorded CD-Rs on the commercially available CD-Rs CD player reproduced. The critics rated the sound quality in the same way as before the irradiation. The results of the evaluation show that the sound quality did not change and that the excellent sound quality was maintained.

Examples 15, 16

Preparation of the CDs

Substrates (diameter: 120 nm, thickness: 1.2 mm) on which digital signals of the respective nine musical compositions listed in Table 2 were recorded as pits in the surface of the substrates were recorded using transparent polycarbonate pellets (PANLITE AD5503, manufactured by Teijin Co.) molded by injection molding. A light-reflecting layer with a layer thickness of 150 nm was formed by vapor deposition with Ag on the surface of each polycarbonate substrate on the surface of which the pits were formed. Thereafter, a UV curing type plastic (SD-310, manufactured by DaiNippon Ink and Chemicals Co., Ltd.) was spin-coated on the light reflecting layer, with the rotation speed being varied between 50 rpm and 5000 rpm , After the application, the ultraviolet-curing resin was cured by irradiating ultraviolet light with a high-pressure mercury lamp as described above to form a protective layer having a thickness of 8 μm.

A Stabilizing layer or a colorant layer and a stabilizing layer were formed on the protective layer to obtain CD-Rs by different conditions in the same way as in the examples 1 to 10 were varied. The position of the center of gravity essentially coincided with the middle of the plate.

Four music critics listened to the sound reproduction obtained by reproducing the obtained CD-Rs on a commercially available CD player. The critics rated the sound quality in the same way as in the previous examples. The results of the evaluation are shown in Table 1. As shown in Table 1, the CDs which had a stabilizing layer having a density of 1.4 to 4.2 g / cm ³ on the periphery thereof in addition to the colorant layer received high ratings.

Claims (10)

An optical information recording medium comprising: either a plate-shaped transparent substrate on which a recording section is provided, which is formed by a light-absorbing layer in which information can be recorded by laser light, or a plate-shaped transparent substrate having a recording section in which information, which can be reproduced by a laser light, a light-reflecting layer provided on the recording section, and a stabilizing layer made of a material having a density of 1.4 g / cm ³ to 4.2 g / cm ³ and on the light-reflecting layer so that a center of gravity of the optical information recording medium is within a range of 15% of a radius of the optical information recording medium from a center of the optical information recording medium. An optical information recording medium according to claim 1, wherein the stabilization layer is provided with a region, the outside a range of 50% of a radius of the optical information recording medium from a center of the optical information recording medium. An optical information recording medium according to claim 1 and 2, further, a colorant layer between the stabilizing layer and the light reflecting layer, wherein the colorant layer contains a colorant, that one wavelength in a band from 400 nm to 560 nm. An optical information recording medium according to claim 3, wherein the colorant is a colored glaze. An optical information recording medium according to claim 3 further comprising a protective layer provided between the colorant layer and the light-reflecting layer. An optical information recording medium according to one the claims 3 to 5, wherein the thickness of the stabilizing layer is at least 1.5 sometimes bigger than the thickness of the colorant layer is. An optical information recording medium according to claim 1 or 2 further comprising a protective layer provided between the stabilizing layer and the light reflecting layer, includes. An optical information recording medium according to one the claims 1 to 7, wherein the transparent substrate has an average light transmittance of 50% or less with respect to light in a wavelength band from 200 nm to one wavelength, the 50 nm shorter as a reproduction wavelength is, has. An optical information recording medium according to one the claims 1 to 8, wherein the stabilizing layer of at least one of a group is that of an inorganic substance, a thermoplastic Plastic and a UV-curing Plastic is formed. An optical information recording medium according to one the claims 1 to 9, wherein a thickness of the stabilizing layer of 1 micron up to 300 μm.